Which woods can be steam bent?

In Mortise, the hardwoods: white oak and ash bend tightest, then red oak, birch, cherry and walnut, then maple. Pine, fir, SPF, cedar and pressure-treated lumber split and are refused.

Bending ply can be laminated round a form. Any sheet can be kerf bent. Ordinary plywood and pressed boards do not laminate.

What length do I cut a board before bending it?

The cut list gives the flat length, worked out from the bend.

Bending wood: kerf, steam and lamination

The Bend tool N curves a board or a glue-up three ways: by kerfing, by steam bending, or by gluing thin strips round a form. Each method takes the wood it can bend, and Mortise refuses a bend the wood would crack on.

Updated October 15, 2026

A white ash 1×4 kerf bent 90 degrees, with the inside and outside radius and the legs read on the wood

Bend a board

Press N; press it again to step through Kerf, Steam and Lamination.
Click the face that will be on the inside of the bend, where the bend starts.
Set the Bend angle on the dial (it catches at 45, 90, 135 and 180°) and the Radius.
Drag the handles on the wood to slide the bend along the board, change the radius, or set the length of a leg. Press Enter.

A new bend starts at 90° on the tightest radius the wood allows. The inspector shows the Inside radius, which is the form you bend round, and the Outside radius beside it, and the length of each leg, measured to the outside of the bend.

The three methods

Kerf: Saw cuts across the inside face, leaving a skin on the outside that bends. Works on any board, sheet or edge-glued panel. Set the Skin left on the outside and the saw kerf.
Steam: Solid hardwood, softened in a steam box and bent on a form. White oak and ash bend tightest, to about twice their thickness; red oak, birch, cherry and walnut to three times; maple to five. Softwoods, sheets, glue-ups and stock over about 2 inches thick are refused.
Lamination: Thin strips glued up round a form. Works on boards and on bending ply; other sheets do not laminate. Set the number of strips or leave it on auto.

A bend tighter than the wood allows is refused with the radius it would crack at.

Working on bent wood

Every cut and joint works on a bent board: tenons on its ends, mortises in its legs, joins on any face it shares.
A crosscut on a bent board can be placed by height or length to the outside of the bend, and cannot land on the curve itself.
Bent boards cannot be resawn or planed, since no machine follows the curve, and fittings cannot be fixed to them yet.
Glue-ups bend as one.
The cut list gives the flat length to cut; the cut sheet draws the part as bent.

Questions

Which woods can be steam bent?: In Mortise, the hardwoods: white oak and ash bend tightest, then red oak, birch, cherry and walnut, then maple. Pine, fir, SPF, cedar and pressure-treated lumber split and are refused.
Can plywood be bent?: Bending ply can be laminated round a form. Any sheet can be kerf bent. Ordinary plywood and pressed boards do not laminate.
What length do I cut a board before bending it?: The cut list gives the flat length, worked out from the bend.